Related Experiment Videos
Ecto-adenosinetriphosphatase in rat small intestinal brush-border membranes
C Schweickhardt1, I Sabolić, D Brown
1Zentrum Physiologie und Pathophysiologie, Göttingen, Germany.
The American Journal of Physiology
|April 1, 1995
Summary
Researchers identified a novel ecto-adenosinetriphosphatase (ATPase) in rat small intestine brush borders. This enzyme, distinct from alkaline phosphatase, hydrolyzes nucleotides, suggesting a role in nutrient metabolism.
Area of Science:
- Biochemistry
- Cell Biology
- Gastroenterology
Background:
- Ecto-adenosinetriphosphatases (ATPases) are enzymes located on the cell surface.
- Their precise roles in the small intestine remain incompletely understood.
Purpose of the Study:
- To identify and characterize ecto-ATPase activity in rat small intestinal brush-border membranes.
- To differentiate this activity from other membrane-bound hydrolases.
Main Methods:
- Western blotting and indirect immunofluorescence using antibodies against rat liver ecto-ATPase.
- Assays for ATP hydrolysis in intact brush-border membrane vesicles.
- Enzymatic inactivation of alkaline phosphatase (AP) to isolate ecto-ATPase activity.
Main Results:
- A 105-kDa protein, recognized by ecto-ATPase antibodies, was localized to the apical surface of enterocytes.
- ATP hydrolysis was observed, with approximately half attributed to AP.
- After AP inactivation, a Ca2+/Mg2+-activated ecto-ATPase (apyrase) remained, hydrolyzing nucleotides but not AMP or pyrophosphate.
Conclusions:
- Rat small intestine brush borders possess a distinct ecto-ATPase (apyrase) activity.
- This enzyme likely plays a physiological role in the degradation of nutrient nucleotides.